Life ScienceVia Dienekes, The Timing of Selection at the Human FOXP2 Gene:
Krause et al. (2007) recently examined patterns of genetic variation at FOXP2 in two Neandertals. This gene is of particular interest because it is involved in speech and language and was previously shown to harbor the signature of recent positive selection. The authors found the same two amino-acid substitutions in Neandertals as in modern humans. Assuming that these sites were the targets of selection and no interbreeding between the two groups, they concluded that selection at FOXP2 occurred before the populations split, over 300Kya. Here, we show that the data are unlikely under this scenario but may instead be consistent with low rates of gene flow between modern humans and Neandertals. We also collect additional data and introduce a modeling framework to estimate levels of modern human contamination of the Neandertal samples. We find that, depending on the assumptions, additional control experiments may be needed to rule out contamination at FOXP2.
Update: Kambiz has much more.
Comments
The focus has been pretty much on gene transference via sex. Yet there is another possibility, lateral transference via virus, bacteria, or even eukaryote. The mechanism for viral transference of genetic material between cells is pretty well laid out, and I have heard of transference of genetic material from bacterium to eukaryotic cell. While nucleated cell to nucleated cell has not yet been demonstrated, the presence of genetic material in cells of the Devil Facial Tumor Syndrome sarcoma strongly homologous with cells of the Canine Transmissible Venereal Tumor sarcoma, which some have identified as being identical, may be just such a demonstration.
Now, while cell to cell---mediated or direct---transference of genetic material has been shown to occur, the view these days is that this new genetic material---so far as we know---is not expressed in the recipient. I submit that we are wrong on this matter, and that 'gifted' DNA is expressed when there is a way for the recipient to express it. So here's my scenario:
During contact between humans and neanderthals DNA was transferred via virus and/or bacteria. Possibly through direct eukaryotic to eukaryotic cell lateral transfer. Most of this new material was not expressed because the recipient had no way to express it, but some---such as the P2 group---was because the recipient had the tools needed to express it.
Yes, it's me being speculative again, but I think investigating the possibility of nucleated cell to nucleated cell transference of DNA between humans and domestic dogs may bear fruit. Especially when you consider how good dogs are at understanding us and our language. A "proof of concept" sort of thing, and one that might bear fruit in studies of human-neanderthal relationships.
Posted by: Alan Kellogg | April 16, 2008 2:22 AM
Hmmm. Well at least the redhead thing is safe from contamination concerns, since the Neanderthal allele wasn't found among a diverse range of living humans, including the team members.
Posted by: agnostic | April 16, 2008 3:37 AM
Agnostic,
Are we talking about contamination, or transplantation?
Posted by: Alan Kellogg | April 16, 2008 11:45 PM